


galaxies inside my heart

by casfallsinlove



Series: Astrophysics and Tea 'Verse [2]
Category: Supernatural
Genre: Alternate Universe - Modern Setting, Dean Works in a Bookstore, Established Relationship, Explicit Sexual Content, Fluff, M/M, Rimming, astrophysicist!cas
Language: English
Status: Completed
Published: 2014-04-24
Updated: 2014-04-24
Packaged: 2018-01-20 15:28:01
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,431
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1515518
Author URL: https://archiveofourown.org/users/casfallsinlove/pseuds/casfallsinlove
Summary: <blockquote class="userstuff">
              <p>"Castiel is all out of his calming chamomile tea because he’s spent the past week drinking it by the gallon (not that it did much but make him need to pee) and he’s been texting Charlie non-stop, looking for both reassurance and also someone to blame for this whole thing. It was Charlie, after all, who said it was about time he finally did it."</p>
<p>Wherein astrophysicist Cas is baffled by society's arbitrarily assigned relationship timelines, and his childhood best friend and current sexual partner, bookstore owner Dean, is just mad that Cas beat him to it.</p>
            </blockquote>





	galaxies inside my heart

**Author's Note:**

> i'm having so much fun writing this 'verse oh wow 
> 
> look out for a dean and cas as little kids instalment next :)
> 
> (p.s. fic contains bottom!dean and disgusting amounts of fluff)
> 
> also on [tumblr](http://casfallsinlove.tumblr.com/)

Castiel has been planning this for months. Everyone is in on it, except of course Dean. He’s been pulling in favours from everyone he knows, and Cas has never liked social interaction so he doesn’t know all that many people.

He bribed Meg at the American Museum of Natural History with the promise of covering her next three school group tours if she gave him the keys to the planetarium, and he blackmailed the night guard, Gordon Walker, into taking Friday night off (Cas may be socially inept, but it didn’t take long to realise Gordon has been stealing pencils from the gift shop and he plans to use that knowledge to his advantage for as long as he can because Gordon is, as Dean puts it, a ‘giant bag of dicks’). 

He persuaded Sam to keep Dean amused while Cas sets everything up, and he even convinced Crowley, the most unagreeable of his colleagues but also the most easily manipulated, into covering his classes that day.

In short, it should go perfectly.

That doesn’t mean that Cas isn’t the most nervous he’s ever been about anything, and that includes saying no to NASA, because who _does_ that?

He’s all out of his calming chamomile tea because he’s spent the past week drinking it by the gallon (not that it did much but make him need to pee) and he’s been texting Charlie non-stop, looking for both reassurance and also someone to blame for this whole thing. It was Charlie, after all, who said it was about time he finally did it.

_About time_. What is that even supposed to mean? Castiel wasn’t aware there was a set timeline for these sort of events in a relationship.

Four years. He and Dean have been in a sexual relationship for four years now. According to Sam and Charlie and their arbitrary and completely illogical relationship itinerary, this is ‘long enough’. But those four years are just a tiny fraction of the twenty-five years they’ve known each other. Does this mean that that it’s been _too long_? After all, they made similar promises when they were ten years old and hiding in the den they made between Dean and Sam’s beds.

It’s all exceptionally confusing and Castiel decides it’s probably best not to overthink it. He’s not adhering to society’s perplexing relationship rules, he’s doing this because it feels right to do it and because he wants to. Because promises made at the age of ten need to be reaffirmed officially.

So here he is. Sitting on the steps outside the museum in the slowly fading summer sunlight, waiting. Sam is late. Cas’s foot taps restlessly.

It’s another fifteen minutes before Sam’s silver Prius pulls up and Dean’s voice drifts audibly through the open window. “What the hell, Sammy? This isn’t The Roadhouse. If you’re trying to get me to go to some nerdy freaking night exhibition then you are—Cas?”

Having risen to his feet and stepped into Dean’s eye line, Cas smiles and walks down the remaining steps until he’s standing on the sidewalk. He nods at Sam, who looks altogether far too amused, while Dean glances between them in confusion.

“You giving a talk or somethin’?” he asks Cas. It’s not an unreasonable conclusion to come to; Castiel often leads various evening workshops and lectures after the museum has closed.

“Something like that,” he agrees. “Come on.”

“Oh, man,” Dean grumbles, but he gets out of the car. “This is not gonna be a fun evening. No wonder you lied to me, Sam.”

Sam smirks. “No wonder,” he echoes, then mouths ‘good luck’ at Cas and speeds away from the sidewalk.

“Oh, sure, he’s got a get out of jail free card,” Dean complains, then looks at Cas. “I’m sorry, baby. I love you, but I do not love your lectures. Last time that stuffy old professor touched my butt, Cas. My _butt_.”

Castiel chuckles quietly. He isn’t offended. Dean has no problem whatsoever listening to him go on about “stars and shit”, but usually when they’re alone on the roof of their building or curled up on a bench in Central Park or that time they went out to Jamaica Bay.

“It is a very nice butt,” Cas says, fingers dancing in the small of Dean’s back, and Dean shoots him a look.

“Flattery will get you nowhere.”

Cas laughs and takes Dean’s hand instead, tugging him up the steps.

“Seriously, Cas, what’s going on?”

But Castiel doesn’t reply, because he’s been reliably informed that he’s a terrible liar and he knows that Dean will be able to read the answer to that question all over his face.

He takes Dean inside the closed museum and leads him up to the second floor, their footsteps echoing in the empty halls. When they get inside the planetarium, blissfully empty, Castiel says, “I pulled a few strings and we have this place to ourselves all night.”

Dean quirks an eyebrow and pulls back to look at him properly. “Dude. Did you bring me here to have sex? You kinky bastard.” Cas rolls his eyes, both at the assumption and the note of pride he can hear in Dean’s voice.

“No, Dean, I did not. I just thought it would be a nice way to spend the evening.”

“You brought me here on a date,” Dean realises, and Cas doesn’t correct him. “I thought date night was Thursdays.”

Shrugging, he says, “I couldn’t arrange it for yesterday.”

At the front of the theater Cas has set up a picnic, of sorts. Really it’s just a bucket of southern fried chicken and a vast quantity of pie with a six pack of chilled beer.

“Oh god, is that pie?” Dean says, on cue, and when Castiel nods Dean kisses him, a firm press of lips on lips. “You’re awesome.”

“I know,” Cas quips, and steps away to set up the projection that Charlie had helped him specially create. “Take a seat.”

Dean settles onto the blankets Cas has spread out on the stage and takes two of the beers, passing him one when Cas sits down. The remote control is clenched tightly in his hand, palm clammy with his nerves. He plays the projection, the planetarium filling with a dull blue glow as the solar system appears above them.

For a little while there’s nothing but comfortable silence and the sound of eating as Dean singlehandedly consumes most of the food. Castiel occasionally points out various constellations, tells Dean the mythology of them. Dean listens, rapt, because he’s a lover of stories and Castiel knows how to read the stars like one, even if he’s more concerned with the physics than the myths.

Then the visualization changes, and the first letter appears in the sky.

“Huh, looks like an ‘M’,” Dean comments and Cas’s stomach clenches with nerves.

“It is.”

Dean throws him a confused glance and then looks back at the fake constellation, which morphs into an ‘A’.

“You never told me there was gonna be anagrams involved,” he laughs, but Cas can’t look at him anymore. This is all Charlie’s fault.

“M, A, R,” Dean whispers, “Another R… Y…” and then the forkful of pie he was holding clatters to the floor. “Cas. Jesus, _Cas_.”

Castiel stops looking at the stars and watches Dean instead as he stares at each and every letter as it appears, his eyes wide and the food long forgotten.

“’Marry me’,” Dean whispers when the program is over and the visualization goes back to a normal view of the Northern hemisphere. He spins around abruptly and grabs Cas’s shoulders, shaking him, a wild look in his eyes. “Are you fucking kidding me?”

Oh no. All the nightmares Castiel’s had about this moment, all the insecurities and all the doubts are rushing towards the surface. It’s possible he’s going to throw up. In fact, it’s likely.

“Dean?” he tries cautiously, “I thought…” but he can’t find the words and Dean is staring at him in a sort of dazed shock.

“I can’t believe you!” he bursts out, “I was gonna—next week at the… Jesus, I can’t believe you beat me to it. This is like that time in tenth grade when you tripped me and got a home run and Coach gave you the special glove.”

“I didn’t trip you, it was—” Cas pauses, registers what Dean is really saying. “Wait, does this mean you’re saying yes?”

Hope floods into him as Dean smirks. “Wow, Cas, I thought you were meant to be smart.”

“You _are_ saying yes?”

He sighs and shakes his head. “Get the fuck over here so I can kiss you, dumbass.”

A shocked laugh huffs out of Castiel involuntarily and he crawls across the small gap until Dean can wrap his arms around his waist and pull him close and smash their mouth together. Dean kisses the yes into Cas’s mouth, murmuring it over and over and touching him everywhere with frantic hands until they’re both grinning too hard and have to slow it down.

“I think we should go home now,” Cas growls, fingers fisted in Dean’s shirt.

“Fuck, yes.”

\--

Dean wakes up early the next morning to sunlight streaming through the curtains and hitting his face. For a second he can’t remember why he feels so happy, and then it all comes rushing back. He grins and rolls over.

"Hey, Cas," he whispers. Cas is sprawled out on his stomach and snoring so Dean pokes him none-too-gently between his shoulder blades. "Baby, wake up."

Groaning, Cas pushes his face into the pillow. "Castiel is sleeping right now, please leave a message."

"Wiseass," Dean complains, and charitably drapes himself over Cas's back to share body heat. And also nudge his morning erection into the crease of Cas's boxer-clad ass like the real gentleman he is. "We’re engaged," he says, then kisses lightly just behind his ear. “Cas, we’re _getting married_.”

Finally, and with a shitload of unnecessary grumbling and errant elbows because he is a menace before he's had at least three cups of coffee, Cas blinks awake and rumbles, "Yes we are."

"We are. You know what that means?"

"We’re entering into a long-term committed relationship with each other?"

Dean rolls his eyes. "No, you doofus. It means we have the perfect excuse to stay in bed  _all day long_." He punctuates the end of this sentence with three rolls of his hips, until he can feel Cas trembling finely underneath him. 

"I guess we can ask Sam to cover the store," he agrees shakily.

Pleased with this decision, Dean noses into Cas's hair and hums his approval. He presses light, breathy kisses down the back of Cas's neck and along his shoulder. "We should watch movies today," he whispers, even as he tangles their legs together. "Get some popcorn, few beers. We haven't done that in a while." 

Dean slides a hand under Cas's belly, shifting lower until he can tuck a pinky finger into the waistband of his boxers. Cas gasps. "Yes—yes, that would be nice."

"Or," Dean adds casually, pushing himself up until there's enough room to drag the underwear over the swell of Cas's butt. "We could take a walk. Maybe drive out to Breezy Point? Go to that coffee place you like after?"

"Dean..." Cas exhales, his hips jerking minutely against the mattress. 

Biting his lip to keep himself from grinning, Dean uses his knees for leverage and swirls his tongue in a small circle at the top of Cas's spine, before kissing his way down it. He stops just before his ass and Cas whimpers. "We could even go to that store, the one that imports stuff from England, get you some of that elderflower tea shit you were geeking out over. I mean, what the hell is _elderflower_ , anyway?" 

“A plant,” Cas deadpans, because his default setting is snarky little shit. Then, "Stop teasing me, Dean," he whines, rutting against the mattress in earnest now that Dean's shifted some of his weight off him. "You're the one who woke me up at this ungodly hour for sex, so follow through."

Dean laughs and palms Cas's waist with both hands, squeezing lightly. "Who says I woke you up for sex?"

"Your raging hard on," he deadpans, and grinds his ass up against Dean to make his point. 

"Touché," Dean admits breathlessly, and definitely does not _yelp_ when Cas bucks him off and rolls them until he’s reversed their positions and has Dean pressed face-down into the mattress.

Sometimes, when he stops to think about it, he can't believe that they haven't been doing this their whole entire lives. Well, from puberty onwards. It's been four years since they pulled their heads out of their asses and wised up to the fact that oh yeah, they sort of love each other in more than a best-friends way, and it's been so damn easy to fall into this physical relationship with Cas, like it was the only thing ever missing.

Well, actually at first it had been weird and awkward and there was a lot of 'oh god I'm touching Cas's dick' hysteria, until Cas had taken the upper hand, thrown Dean on the bed and proceeded to ride him like a Texas cowboy. After that, pretty much everything stopped being awkward and started being really fucking awesome. 

Cas skims his hands down Dean’s back, his mouth following in their wake, and palms two handfuls of Dean’s butt, spreading him open. 

"Oh god," Dean moans, his fingers clenching in the sheets. Cas kisses one ass cheek, then the other, taking his sweet time because Dean has never been very patient and he's even less so in bed and Cas likes to drive him to the brink of insanity before he gives in and fucks him.

Dean shivers. 

"On your knees," Cas murmurs and Dean pushes up immediately, and wait a minute, since when was Cas the one giving all the orders? Dean was gonna be the captain of this ship—except then Cas drags his tongue down the crease of Dean’s ass, circling his hole, and Dean whines incoherently and decides Cas can take charge whenever he damn well pleases.

Fuck, Dean loves when they do this. It’s so primal, so downright filthy, and he goes into that blissfully blank headspace that he always goes into during sex where he can do nothing but cling to the sheets for dear life. 

Cas opens him up with his tongue—totally unnecessarily because Dean’s still pretty loose from all the smokin’ hot sex they had last night, which just goes to prove how insatiable his boyfriend, _fiancé_ , is really—and then pushes into him nice and slow.

Cas plasters his front to Dean’s sweaty back, kissing the nape of his neck and breathing hot and damp against his skin. His thrusts start small, easing Dean into it, and then pick up the pace until his hips are snapping with purpose, jolting Dean’s entire body and making the headboard slam against the wall.

“Jesus fuck,” Dean groans appreciatively, back arching and hands scrabbling at the pillow under his head. Cas continues to fuck him, deep and steady and sure, for a long time, then finally, mercifully, reaches under him and jerks him off until Dean is coming and coming against the sheets, his lips parted in a silent scream. Another couple of minutes and Cas stills too, tipping over into his own orgasm, shuddering and moaning like the pornstar Dean suspects he was born to be.

They pant for a while, trying to catch their breath, then Cas rolls off him and sprawls out on the bed. Sweat beads on his forehead and Dean considers leaning over and licking it off but that will lead to more shenanigans and after last night and now this morning, he doesn’t think he’ll be able to get it up ever again. Well, not for a few hours, at least.

Cas grins at him and Dean reaches over and pushes an errant cowlick back from his damp forehead. “Best husband-to-be ever,” he says with feeling, and Cas snorts in amusement.

Sleepiness washes over Dean, in the way it always does after a satisfying orgasm, and he pulls Cas closer by the waist and nuzzles into his hair. “Nap now,” he mumbles, and Cas imperiously grunts something back about not being able to fall asleep again now he’s been woken up, but Dean’s already tuning him out and letting his eyes drift shut.

He wakes a while later to a light touch brushing down his cheek, across the bridge of his nose, over his closed eyelids. 

"What’re you doin’?" he grumbles, like this is the first time this has happened. (It isn’t.)

Cas’s finger stills, comes to rest in that dip under Dean’s bottom lip that he’s sort of obsessed with. “Nothing.”

Cracking open an eye, Dean squints blearily. “Were you looking for constellations in my damn freckles again?”

Cas smiles, soft and sleepy. “I found Ursa Minor right here,” he says, and brushes his fingertip from the crease of Dean’s eye and along the ridge of his cheekbone.

"You’re such a fuckin’ weirdo," Dean tells him, full of affection. He glances over at the clock on the nightstand and groans. "We should probably get up."

They stumble into the shower together, which inevitably leads to soapy back rubs and sloppy kisses, then dress in casual wear—or in Cas’s case, a nerdy New York Hall of Science volunteer t-shirt. Dean would complain about having just promised to spend the rest of his life with such a geek, only Cas looks hot in t-shirts and also Dean’s seen him lead workshops for kids about space at NYSCI and it’s actually sort of adorable.

Cas makes a fruit tea in his Jupiter mug (seriously, fucking _nerd_ ) while Dean pours out a bowl of Lucky Charms, but at the thoughtful little moue of Cas’s mouth asks, “What’s up?”

“Hm? Oh, nothing. Just… should we have rings?”

Dean blinks at him. “I hadn’t really thought about it.”

Still dipping the teabag in and out of his tea, Cas says, “I didn’t buy one because I wasn’t sure what style would be best. And usually men don’t wear engagement rings.”

“We don’t have to have them,” Dean offers, and honestly, he wouldn’t mind. He wears his dad’s wedding ring anyway and Cas never has been a big jewelry sort of person. “I’m not a chick, I’m not expecting diamonds.”

“Okay,” Cas agrees, and drops a pomegranate-flavoured kiss to Dean’s lips.

But the thing is, Dean can’t stop thinking about it. He spends the next week riding this cloud nine high, telling everybody he knows and every customer that comes through _Little Dickens_ ’ door about how he and Cas are getting married, but he has nothing to show them to _prove_ it other than the occasional hickey on his neck.

So he buys a ring. A plain, silver band, nothing fancy about it at all, and when Denise the sales assistant tiredly asks him if he wants it engraved, Dean says yes. He may not know the stars or science but he does know words and does know books. He goes with McCarthy’s ‘The Road’ and writes the quote on the slip of paper Denise hands him; _You have my whole heart. You always did._ She nods and he agrees to return the next day to pick it up.

When Cas comes into the bookstore at lunchtime a few days later with a sandwich from Dean’s favourite deli for him (because Cas is the best), Dean gives him the ring.

Cas stares at it for a whole nerve-wracking minute, which is stupid because _he_ was the one who proposed, and Dean starts to say, “It’s really fucking cheesy, oh man, I shouldn’t have—”

But then Cas is kissing him, and kissing him, and whispering, “It’s perfect,” and kissing him some more, so Dean shuts up.

He squeezes Cas’s waist and tells him, “It’s Cormac McCarthy and it’s sappy as all hell, but y’know, s’true.”

Cas beams at him and slides the ring onto his finger. Dean has a moment of relief to think ‘thank god it fits’ before he’s got six-feet of awkward fiancé in his arms and a bony chin digging into his shoulder. “I’m gonna get you one right now,” Cas promises, like a kid, and practically runs from _Little Dickens_ leaving nothing but a meatball sub and lingering touch of lips to Dean’s cheek behind. 


End file.
